Senate Republican candidate Ben Sasse / Eric Gregory, AP

by Fredreka Schouten and Christopher Schnaars, USA TODAY

by Fredreka Schouten and Christopher Schnaars, USA TODAY

WASHINGTON - An outside political committee has spent thousands of dollars on signs and billboards to boost Florida Democrat Gabriel Rothblatt's long-shot bid for Congress.

Every dollar the super PAC has collected - $225,000 - has come from his parent, Martine Rothblatt, the CEO of a Maryland-based biotech company.

The pro-Rothblatt "Space PAC" is one of dozens of deep-pocketed super PACs financed by a handful of donors - some of which have close ties to the candidates they support. More than 40 super PACs that have raised at least $100,000 since Jan. 1 list fewer than five donors on campaign-finance reports, a USA TODAY analysis shows.

Federal candidates can't accept donations larger than $2,600 for a primary or general election. Super PACs can accept unlimited corporate, union and individual donations as long as they operate independently of the candidates they back. It's perfectly legal for candidates' mothers, siblings, grandparents and other relatives to finance super PACs. Campaign-finance watchdogs argue the practice demonstrates the broken state of election laws and regulations.

In an interview, Gabriel Rothblatt said he was unaware of the super PAC's activities until he saw the committee's yard signs promoting his candidacy in late April. He said he has taken pains not to communicate with his father.

"You don't want to, in a casual conversation, cross a line that can turn around and bite you," Gabriel Rothblatt said.

Martine Rothblatt, founder of Sirius Satellite Radio and the CEO of United Therapeutics, underwent gender reassignment surgery in the 1990s and identifies as female. She did not respond to interview requests.

Gabriel Rothblatt, 31, needs all the financial help he can get in his first political campaign. His opponent, three-term Rep. Bill Posey, R-Fla., has a more than 13-to-1 fundraising advantage over Rothblatt.

Though the outside spending may help boost Rothblatt's name recognition, he said the super PAC has drawbacks. He's gotten more than a half-dozen complaints from officials about improper placement of the super PAC's yard signs.

"I can't do anything," he said. "I can't touch the signs myself. It would look like I'm coordinating" with the political action committee.

Candidates' relatives have funded other super PACs active in this year's midterm elections for Congress.

In Nebraska, the Ensuring a Conservative Nebraska super PAC got all of its $100,000 from Rupert Dunklau, the retired great-uncle of Republican Senate candidate Ben Sasse. Most of the money funded a TV attack ad against Sasse's unsuccessful rival in the primary in May.

Neither Sasse's campaign aides nor Dunklau returned telephone calls and e-mails. In a statement published in The Omaha World Herald this year, Sasse said, "Neither I nor my campaign coordinated any messaging or spending with this group."

In Oklahoma, state Rep. Mike Turner, who put more than $500,000 of his own money into his U.S. House race this year, was supported by a super PAC funded entirely by family sources. Turner, who lost a six-way GOP primary in June, did not respond to an interview request.

Paul Ryan of the Campaign Legal Center, which favors more restrictions on political spending, said some super PACs are "sham independent groups."

"The law is a mess right now and doesn't require anything remotely resembling true independence," he said. "It's easy to get around the contribution limits. Instead of cutting a huge check directly to a candidate â?¦ you cut that huge check to a group that was set up by a former employee of the candidate or a family member of the candidate."